The present invention relates to a knockout mechanism for a high-speed automatic cold heading machine and more particularly to a knockout mechanism of a heading machine for bolts whose body and head are substantially different in size and of somewhat complex forms. The heading macnine herein referred to is capable of forming rivets, tubular rivets, socket-head screws, hexagon-head screws, wood screws and bolts thereof, machine screws, automobile bolts, tapping screws and screws having cross recess style round-heads, counter sunk heads, oval heads, square heads and the like.
A conventional knockout mechanism for heading machines generally used in the art is shown in FIG. 1. A rocker arm 2 is pivotedly connected to a pin 21 and moves with the pin 21 as the fulcrum. The lower end of the arm 2 is fixed with rollers 22 which are impacted by a cam 31 driven by a rotating shaft 3. An ejecting rod 1 is correspondingly impacted by an adjusting bolt 5 fixed at the upper end of said rocker arm 2 to eject the finished blank 4 out of the dies 6.
The construction mentioned above is complex in structure, especially since the rollers 22 of the rocker arm 2 are impacted once for every revolution of the cam 31 on the rotating shaft 3 to move the rocker arm 2 for accomplishing the knockout operation. Thus, it has been found that the impacting forces or shock load are always applied to some specific portions of the parts for the ejecting operation, whereupon the parts wear readily. Errors will then easily occur and the timing for performing wire feeding and cutting operations, and upsetting and knockout operations cannot easily and accurately be coordinated during the sequence of operations. Thus, it is impossible to obtain a hign-speed and very stable heading operation.